The Stags were trailing for much of the first round tie at the New Lawn after struggling to make an impact with their 4-3-3 formation.
But Holdsworth changed tack in the second period, bringing on Ryan Williams and Craig Dobson down the flanks.
And it was from a deflected Williams centre that Scott Garner levelled Jared Hodgkiss' first half opener.
"When we went 4-4-2 we got more ball out wide and we have gone away from home and got a draw, so it worked," said Holdsworth.
"When we got the ball out wide we looked more dangerous and Dobson almost got in a couple of times.
"The little man (Ryan Williams) came on and together with Dobson did a decent job."
Holdsworth feels that striker Kyle Perry should have had a first half penalty that could have changed the course of the game.
He believes the Port Vale man sometimes gets the rough end of the stick where decisions are concerned.
Holdsworth said: "We had what I thought was a conclusive penalty in the first half. Kyle Perry doesn't always get the best of decisions because of his size.
"Apart from the sending off in the Stevenage game he has a good disciplinary record and I explained that to the referee at half-time."

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Holdsworth praises Marriott for keeping Stags in FA Cup
CHAD.co.uk, 07 November 2009
By Stephen Thirkill
BOSS David Holdsworth praised goalkeeper Alan Marriott for keeping Stags in the FA Cup after the shot-stopper pulled off two wonderful saves against Forest Green at The New Lawn.

The central defender netted his side's goal at the New Lawn – and in doing so ensured he will play for club not country a week on Tuesday.
He hopes the Stags can seal a place in round two to go some way to making up for not being able to play internationally in Poland.
"I was saying to Daryl Clare in training in the week that I wasn't really getting near to scoring," said Garner. He said to try going in different places and I suppose it paid off. I will take the goal as it keeps us in the FA Cup.
"Jonah (Luke Jones) and I know we have to keep getting in the goals and we need to get one between us every three or four games if we can.
"I'm gutted that this one makes me miss the England game – I would have rather gone through and played in the England game.
"If we don't go through now then I won't be very happy, but I think we should be confident with home advantage.
Garner admitted Mansfield were far from at their best in Gloucestershire.
He said: "I think we struggled to get going. We didn't get into the game in the way we normally do – which meant we had to work harder.
"We didn't keep the ball well. We just looked to launch the ball and expected our strikers to win it.
"It was a case of creating our own problems at times by letting the ball bounce and things like that.
Garner was thrown up front in the closing stages and said the goal came somewhat out of the blue.
"It was getting frustrating because we were going long in the closing stages and everything was running through to their keeper," he said.
"It was a slow game and we couldn't keep the attack going and put any kind of pressure on them. But we persevered and got our rewards and now we take them back to our place."

At times the Stags goalkeeper was the only thing between Forest Green and their progression to the FA Cup second round.
But his efforts were rewarded when Mansfield drew level in the dying stages.
"The way the game was going with us 1-0 down it is sometimes easier to go out and make your saves," said Marriott.
"But when people pop up and score a late equaliser then people sometimes realise what a good job you have done.
"If you go on to lose, then people don't always notice – and that's life – but it is nice to get credit in a game like this."
Marriott, who bounced back after conceding the penalty in the previous week's 1-1 draw with Histon, was critical of his team's display.
But he felt the Stags' excellence on the bench played a key role in them turning the game around late on.
Marriott said: "We didn't do ourselves any favours. We looked a bit leggy and you have those days sometimes.
"I got up at 6am along with some of the other lads, but you can't use that excuse, People who do 9am to 5pm jobs work much harder than footballers.
"For some reason we got ourselves in the mindset that we had to hit it long. They are going to be a little disappointed they didn't go through when they had the lion's share of the possession and chances.
"But I think the lads who came on in the second half did fantastically well and it is nice to have that quality on the bench."

That's the view of manager David Holdsworth, who admitted his side were second best for long spells of Saturday's game at the New Lawn.
The Stags trailed to a Jared Hodgkiss first half strike and Rovers might have put the game beyond Mansfield, but for several crucial saves from experienced ex-Lincoln man Marriott.
Then, with three minutes to go, Scott Garner scored a leveller to take the game back to Field Mill – and left Holdsworth counting his blessings.
"Alan Marriott kept us in the cup. He made two or three saves that kept us in the game," said Holdsworth.
"Sometimes players can make the difference – a goalkeeper, a striker, a player off the bench.
"We have Alan Marriott to thank for keeping our cup run going. I'm delighted with a replay because they were the better team.
"We had some good chances, but not enough quality. Our players set very good standards and have won a lot of games.
"But our performance was poor in midfield and all the way through and the boys know that.
"We started all right, but there was indifferent performances from certain players. We have set high standards and if you drop them then you can get exposed sometimes
"But I am not going to single anybody out. There is no point chastising players because they are not doing it on purpose.
"The fans showed tremendous spirit again and we are very thankful for their continued vocal support.
"We at least sent them home with something but we are not trying to kid anyone at home – we didn't play as well as we can but we are still in there."